Vacuum Technology Know How - Triumf

Pfeiffer Vacuum
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Vacuum Technology
The ions thus formed are also extracted to the mass filter through a small opening to the lowpressure
side. This ion source offers two crucial advantages for examining the composition
of the gas in sputtering processes. On one hand, the analysis is performed at an ion source
pressure that is up to three orders of magnitude higher; i.e. a higher concentration of residual
gas can be tolerated in the vacuum chamber. On the other hand, the hot filament is not in
direct contact with the sputtering process. This avoids contamination by the hot cathode for
sensitive processes.
Standard PrismaPlus TM
ion source
The PrismaPlus mass spectrometer from Pfeiffer Vacuum is equipped with this robust and
highly sensitive ion source. It is an ion source that is especially suitable for residual gas
analysis. Its design is comparable to that of a lattice source; like the lattice ion source, it has
two cathodes, thus affording particularly secure operation. Both an open version as well as
a gas-tight version with gas inlet in the axial direction are available.
All ion sources described here ionize by means of electron collision. The ion sources can be
categorized into two groups:
Open ion sources are used if the process gas is to be analyzed and additional pressure
reduction is not required
Closed ion sources are used in analytical applications, for example, in order to require
only small volumes of gas or to increase sensitivity relative to the substrate of the
vacuum system
Open Design Gas-Tight Design
Figure 4.14: PrismaPlus ion source
Closed ion sources are used in combination with a differentially pumped system (Figure 4.13)
in order to analyze higher-pressure gases.
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